Artificial turf infill and artificial turf including the same

ABSTRACT

An artificial turf is provided. The artificial turf includes a pile fabric having a backing, pile elements extending upwardly from the backing, and an infill layer filled on the backing such that the pile elements are at least partially embedded in the infill layer. The infill layer includes an elastic infill and a high-hardness resin infill.

BACKGROUND

1. Field

The disclosed technology relates to an artificial turf infill, and anartificial turf including the same.

2. Description of Related Art

An artificial turf was first developed in U.S.A. and has been used since1965. The artificial turf has a structure in which fibers made ofplastic filament extend upwardly from an underlying backing. Theartificial turf however gradually decreased in usage due to its highhardness compared to the natural turf, and the slippery surface thereofcausing a user's slippage. In the late 1990s, the artificial turf wasenhanced with elasticity and low sliding resistance by erecting longfibers of soft plastic filament on the underlying backing, and thenfilling the spaces between the long fibers with an infill such as smallchip of rubber and/or sand, resulting in a prevalent use for footballfields, baseball fields, etc. including playgrounds in these days.

The artificial turf infill can be used in various types: the type usingonly sands, the type using only rubber chips made from waste tires, thetype using a two-layered structure in which sands are spread on a lowerlayer and rubber chips are spread on an upper layer, the type using amixture of rubber chips and sands, the type using a mixture of rubberchips and sands coated with rubber, and so on.

SUMMARY

In one embodiment, an artificial turf includes a pile fabric having abacking and pile elements extending upwardly from the backing, and aninfill layer filled on the backing such that the pile elements are atleast partially embedded in the infill layer. The infill layer includesan elastic infill having a hardness ranging from 40 to 90 Shore A, and ahigh-hardness resin infill having a hardness ranging from 50 Shore D to120 Rockwell R. The high-hardness resin infill includes a syntheticresin matrix and an inorganic filler dispersed in the synthetic resinmatrix.

In another embodiment, a method of producing artificial turf includesproviding a pile fabric having a backing, and pile elements extendingupwardly from the backing, providing a high-hardness resin infill havinga hardness ranging from 50 Shore D to 120 Rockwell R, the high-hardnessresin infill including a synthetic resin matrix and an inorganic fillerdispersed in the synthetic resin matrix, mixing the high-hardness resininfill with an elastic infill having a hardness ranging from 40 to 90Shore A to form an infill mixture, and filling the infill mixture on thebacking to form an infill layer such that the pile elements are at leastpartially embedded in the infill layer.

In still another embodiment, an artificial turf includes a mixture of ahigh-hardness resin infill and an elastic infill. The high-hardnessresin infill includes a synthetic resin matrix and an inorganic fillerdispersed in the synthetic resin matrix—and has a hardness ranging from50 Shore D to 120 Rockwell R. The elastic infill has a hardness rangingfrom 40 to 90 Shore A. The high-hardness resin infill and the elasticinfill are mixed in a weight mixing ratio ranging from 1:9 to 9:1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating an embodiment ofartificial turf filled with an artificial turf infill;

FIG. 2 illustrates an embodiment of a high-hardness resin infill usedfor an artificial turf infill; and

FIGS. 3A and 3B are cross-sectional views illustrating other embodimentsof artificial turf filled with an artificial turf infill.

DETAILED DESCRIPTION

As described in the “Description of Related Art,” an artificial turfinfill may be used in five types, each of which has drawbacks. In thefirst type of the infill using only sands (U.S. Pat. No. 4,044,179), theinfill may harden the entire artificial turf. Thus, when slipping down,a player may be severely injured to his/her head. Further, the slipperysurface of the artificial turf may cause friction abrasion to playerswhen impacting the turf and deterioration of the efficiency of theplayground. In addition, the sands are broken into fine particleswith—time, so that the fine particles are filled between otherparticles. As a result, the infill becomes gradually hard. In the secondtype using only rubber chips (U.S. Pat. No. 5,976,645), the infill hasextremely high elasticity, which may cause an injury to a player'sankle, knee, waist, etc. and strain to calf muscles of the player. Inthe third type of the infill using a two-layered structure of rubberchips and sands (U.S. Pat. No. 4,337,283), the infill alleviates—thedrawbacks of the first and second type infills. However, the sands arealso broken into fine particles with the lapse of time, so that the fineparticles are filled between other particles. As a result, it isdifficult for the infill to avoid becoming hard. Further, it isimpossible to overcome all the drawbacks of the rubber chips spread onan upper layer (i.e. the drawbacks of the second type using only rubberchips). In the fourth type of the infill using a mixture of rubber chipsand sands, the infill can eliminate all the above drawbacks. However,there is a great difference between a specific gravity of the rubberchip (from 1.15 to 1.20) and that of the sand (from 1.90 to 2.25), andthus the infill is separated up and down during use. Therefore, theinfill is transformed into the third type using a two-layered structureof rubber chips and sands. Even if the rubber chips having a specificgravity similar to that of the sand are used in place of the rubberchips made from waste tires, the sands will compact and the infill willbecome quite hard. In the fifth type of the infill using a mixture ofrubber chips and sands coated with rubber (U.S. Pat. Application20080145574), the infill can overcome the drawback of sand compactionand hardening described in the fourth type. However, the coating of thesands costs a great deal, so that using the infill is economicallydisadvantageous. In addition, if an adhesive force of the coating isinsufficient, the coating is worn out with time.

Among qualities of natural turf and artificial turf used for footballfields, a surface hardness has a great influence on playability and riskof player injury. For this reason, the Federation Internationale deFootball Association (FIFA) has established quality standards forartificial turf on the basis of surface hardness measurement (FIFARECOMMENDED 2 STAR/1 STAR (2004. 7. 1) and IRB regulations (2004. 4)).The surface hardness measurement is to measure a peak shock of impact,Gmax, by using the test method of ASTM F355, which tests shock-absorbingproperties of playing surface systems such as an artificial turf. Gmaxvalues express a ratio of the maximum acceleration (deceleration)experienced during an impact with the surface undergoing testing, to thenormal rate of acceleration due to gravity. Thus, the higher the Gmaxvalue, the lower the shock-absorbing properties of the playing surfacesystems. If Gmax value is within a range between 80 and 200, the turf isusable. If Gmax value is beyond this range, the turf should be replaced.In detail, when Gmax is less than 80, the turf is too low in hardnessand too high in elasticity. In contrast, when Gmax exceeds 200, the turfis too high in hardness and too low in elasticity. Particularly, in thelatter case, when falling down, a player has a possibility of receivinga serious injury to his/her head.

When the infill of the artificial turf is formed of only sands, Gmaxvalue may exceed 400. When the infill of the artificial turf is formedof only rubber chips obtained from a waste tire, Gmax value may bewithin a range between 40 and 70. When the infill of the artificial turfincludes a thick rubber chip layer and a thin sand layer, Gmax value maybe less than 80. When the infill of the artificial turf includes a thinrubber chip layer and a thick sand layer, Gmax value may exceed 200.Although-Gmax is adjusted to be within a range between 80 and 200 byadjusting thickness of the rubber chip layer and the sand layers, athickness ratio of the layers may be slightly varied by continuousbounds of a ball and kicks of the players, a gust of wind, a heavy rain,and so on. Thus, the artificial turf may be divided into regions thatpartially meet the Gmax requirements and the other regions that do notmeet the Gmax requirements, so that the artificial turf can benon-uniformly varied.

In the case sands are used as the infill, some of the sands are brokeninto fine particles with the lapse of time, so that the fine particlescan fill the spaces between the other particles. Thereby, the sands areagglomerated in a hard state, and thus Gmax value may exceed 200.Further, as it is known that the sand is used as a raw material of asand paper, the sand wears away the artificial turf, so that the sandcan reduce the duration of the artificial turf. Furthermore, the sandshaving porous structures may absorb sweat or blood of players, molds,excrement of animals, etc., thereby containing—various microbes such asbacteria. In this manner, the sands have many factors harmful to theplayer's health. In addition, the sands of the artificial turf surfacemay cause a severe abrasion on the player's when the player-falls downor slides.

Thus, the embodiments of the inventive concept are directed to providingimproved artificial turf including a new infill material.

Now, references will be made in detail to some embodiments, examples ofwhich are illustrated in the accompanying drawings. It should beunderstood, however, that the drawings and detailed description relatingthereto are not intended to limit the claimed subject matter to theparticular form disclosed. Rather, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the claimed subject matter. It will be readily understoodthat the components of the disclosure, i.e. the components generallydescribed and illustrated in the drawings herein, could be arranged,substituted, combined, and designed in a wide variety of differentconfigurations. Thus, all the components will be explicitly referred bythose skilled in the art and form a part of the disclosure.

FIG. 1 is a cross-sectional view illustrating an embodiment ofartificial turf filled with an artificial turf infill. Referring to FIG.1, the artificial turf includes a pile fabric 11 having a backing 10 aand pile elements 10 b extending upwardly from the backing 10 a, and aninfill layer 12 filled on the backing 10 a such that the pile elements10 b are at least partially embedded in the infill layer 12. Here, theinfill layer 12 includes an elastic infill 13 and a high-hardness resininfill 14. Further, the high-hardness resin infill 14 may include asynthetic resin matrix and an inorganic filler dispersed in thesynthetic resin matrix.

The infill layer 12 may include a mixture in which the elastic infill 13is uniformly mixed with the high-hardness resin infill 14. For example,the infill layer 12 may include a mixture of the elastic infill 13 andthe high-hardness resin infill 14 at a weight ratio ranging from 1:9 to9:1. The weight ratio may be properly adjusted according to the physicalproperties required for the artificial turf.

The artificial turf may be produced as follows. First, the pile fabric11 is provided. The pile fabric 11 has the backing 10 a and the pileelements 10 b extending upwardly from an upper surface of the backing 10a. Then, the high-hardness resin infill 14 including the synthetic resinmatrix and the inorganic filler dispersed in the synthetic resin matrixis provided. Subsequently, the high-hardness resin infill 14 and theelastic infill 13 are mixed to form an infill mixture. Next, the infillmixture is used to form the infill layer 12 filled on the backing 10 asuch that the pile elements 10 b are at least partially embedded in theinfill layer 12. Thereby, the artificial turf can be produced. Thehigh-hardness resin infill 14 may be prepared by mixing the syntheticresin matrix with the inorganic filler—and then extruding andpelletizing this mixture.

The backing 10 a serves to fix the pile elements 10 b and may have aloose texture or a perforated structure to drain well. The backing 10 amay be in contact with the ground (not shown).

The pile elements 10 b are attached to the backing 10 a to serve as thesurface of the artificial turf. Each of the pile elements 10 b may bemade of plastic filament such as polyethylene, polypropylene,polyvinylidene chloride, nylon, or the like and may contain a greenpigment to give the feel similar to the natural turf.

The infill layer 12 may be formed by filling an empty space between—thepile elements 10 b with the infill in order to give the artificial turfwith elasticity and low sliding resistance. Because the infill layer 12has a great influence on performance of the artificial turf, the infilllayer 12 is required to have proper and consistent elasticity, hardness,and drain performance. The mixture of the elastic infill 13 and thehigh-hardness resin infill 14 is used as the infill layer 12 so that allthe characteristics required for the artificial turf infill can beexerted.

The elastic infill 13 may be comprised of recycled chips of a wastetire, thermoplastic elastomer (TPE) chips, special rubber chips orcombinations thereof in order to give elasticity to the artificial turf.The recycled chips of waste tires may be obtained by pulverizing thewaste tires. The special rubber chips may be obtained by measuringrubber such as ethylene propylene diene monomer (EPDM) rubber,isobutylene isoprene rubber (called butyl rubber), Hypalon rubber, orneoprene rubber along with compounding chemicals such as a vulcanizingagent, a vulcanizing accelerator, a vulcanization active agent, aninorganic filler, a softener, a processing aid, an anti-aging agent, andthe like, mixing the measured materials, vulcanizing the mixture into aplanar rubber, and pelletizing the planar rubber using a mill. Further,the TPE chips may be obtained by mixing TPE, such as styrene butadienestyrene block copolymer (SBS), styrene isoprene styrene block copolymer(SIS), styrene ethylene butadiene styrene copolymer (SEBS),thermoplastic polyolefin (TPO), thermoplastic polyurethane (TPU) or thelike, with an inorganic filler, a softener, etc. using an extruder andthen pelletizing the mixture. The elastic infill 13 may have a diameterranging from 0.3 mm to 3.0 mm, and preferably from 0.5 mm to 2.0 mm. Theelastic infill 13 may have a Shore A hardness ranging from 40 to 90,preferably from 50 to 80, and more preferably from 55 to 75, withoutplacing restrictions on the other physical properties. If the hardnessof the elastic infill 13 is less than 40 Shore A, the elastic infill 13gets too high elasticity, so that the players have a probability ofreceiving injuries to their ankles, knees, and waists. If the hardnessof the elastic infill 13 exceeds 90 Shore A, Gmax value may exceed 200when the elastic infill is mixed with the high-hardness resin infill, sothat the players can receive a lethal injury to their heads when fallingdown. An amount of the mixed inorganic filler may be properly adjustedsuch that the elastic infill 13 has proper hardness and specificgravity.

The high-hardness resin infill 14 included in the infill layer 12 alongwith the elastic infill 13 may be a composite of a synthetic resin andan inorganic filler.

FIG. 2 illustrates an embodiment of a high-hardness resin infill used inan artificial turf infill. As illustrated in FIG. 2, the high-hardnessresin infill 14 may include a synthetic resin matrix 15 and an inorganicfiller 16 dispersed in the synthetic resin matrix 15. The high-hardnessresin infill 14 has at least higher hardness than the elastic infill 13of FIG. 1, so that the high-hardness resin infill 14 can give a hardproperty to the artificial turf.

The high-hardness resin infill 14 may have a hardness ranging from 50Shore D to 120 Rockwell R, and preferably from 60 Shore D to 110Rockwell R. If the hardness of the high-hardness resin infill 14 is lessthan 50 Shore D, the high-hardness resin infill 14 gets high elasticitydue to synergism with the elastic infill 13, so that the players have aprobability of receiving injuries to their ankles, knees, and waists. Insummer, the temperature of an artificial turf playground may increase upto 70° C. or more. In this case, the plastic chips are conglomerated orstuck to the spikes of the player's shoes to interfere with his/herplay. Further, the duration of the artificial turf infill may bereduced. If the hardness of the high-hardness resin infill 14 exceeds120 Rockwell R, the plastic is too hard, so that the players can beinjured to their heads when falling down although the high-hardnessresin infill 14 is mixed with the elastic infill 13. Further, thehigh-hardness resin infill 14 may cause the artificial turf to berapidly worn out, thereby reducing the duration of the artificial turf.

A material used as the synthetic resin matrix 15 is not particularlylimited so long as the high-hardness resin infill 14 is selected tocover the above hardness range. As an example, when the artificial turfis used in the playground, a good weatherable polymer material may beused as the synthetic resin matrix 15 considering that the artificialturf must be exposed to the external environment for a long time. Forexample, the polymer material used as the synthetic resin matrix 15 mayinclude polyethylene, polypropylene, and ethylene copolymer, which maybe used alone or in combination of at least two thereof. The ethylenecopolymer may have a monomer unit based on ethylene and another monomerunit based on α-olefin having 3 to 20 carbon atoms. The α-olefin mayinclude propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene,1-decene, or the like. As another example, the ethylene copolymer mayhave a monomer unit based on ethylene and a monomer unit based on vinylacetate or acrylate. More specifically, the ethylene copolymer mayinclude ethylene-1-butene copolymer, ethylene-4-methyl-1-pentenecopolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer,ethylene-1-decene copolymer, ethylene-1-butene-4-methyl-1-pentenecopolymer, ethylene-1-butene-1-hexene copolymer,ethylene-1-butene-1-octene copolymer, ethylene-ethylacrylate,ethylene-butylacrylate, ethylene-methacrylate,ethylene-methylmethacrylate, or the like. The ethylene copolymer maycontain the ethylene-based monomer unit of 50 wt % or more when acontent of the whole monomer units thereof is defined as 100 wt %.

When the inorganic filler 16 is dispersed in the synthetic resin matrix15, the hardness and specific gravity of the high-hardness resin infill14 may be enhanced. The inorganic filler 16 may include talc, mica,calcium carbonate (CaCO₃), silica (SiO₂), wollastonite (CaSiO₃), clay,diatomite, titanium dioxide (TiO₂), zeolite, and the like, which may beused alone or in combination of at least two thereof, and preferablycalcium carbonate in cost consideration. The inorganic filler 16 may bein powder form, an average diameter of which may range from 0.1 μm to 5μm.

The inorganic filler 16 may have a content ranging from 20 wt % to 80 wt%, preferably from 30 wt % to 75 wt %, and more preferably from 40 wt %to 70 wt %, with respect to a total weight of the high-hardness resininfill 14. When the content of the inorganic filler 16 is within theabove range, it is possible to obtain the high-hardness resin infill 14having appropriate hardness and specific gravity.

Further, a specific gravity difference between the elastic infill 13 andthe high-hardness resin infill 14 may be 30% or less, preferably 25% orless, and more preferably 20% or less on the basis of a lower one whenthe specific gravity of the elastic infill 13 is compared with that ofthe high-hardness resin infill 14. If the specific gravity differenceexceeds this value, the chips may be separated into upper and lowerparts.

The high-hardness resin infill 14 may be produced to have desiredhardness and specific gravity by properly adjusting kinds and contentsof the synthetic resin matrix 15 and the inorganic filler 16.

The high-hardness resin infill 14 may contain additives typically usedin the art, for instance an antioxidant, a light stabilizer, a heatstabilizer, and a colorant. The high-hardness resin infill 14 may beproduced by mixing a synthetic resin and an inorganic filler with theadditives using a mixer. For example, the synthetic resin, the inorganicfiller, and the additives may be mixed and extruded using a Banburykneader, a Buss kneader, a single screw extruder or a twin screwextruder.

As illustrated in FIG. 2, the high-hardness resin infill 14 may have theshape of an elliptical pellet. The pellet may have a diameter (D)ranging from 0.5 mm to 2.5 mm. The high-hardness resin infill 14 mayhave the shape of a rod, a sphere, or an ellipsoid. The pellet may havea polygonal cross section such as a tetragonal or hexagonal crosssection, as well as the circular cross section.

In one embodiment, the content of the elastic infill 13 and/or thehigh-hardness resin infill 14 in the shape of a mini pellet with adiameter of 1 mm or less in the infill layer 12 is preferably 10 wt % ormore, more preferably 30 wt % or more, with respect to the total weightof the infills 13 and 14.

In a certain case, water may be sprinkled on the surface of anartificial turf for the purpose of managing the artificial turf orinhibiting a rise in the surface temperature of the artificial turf. Forexample, in summer, an artificial turf using black chips obtained bypulverizing tires may reach a maximum surface temperature of 70° C., andan artificial turf using a green EPDM infill may reach a maximum surfacetemperature of 50° C. At this time, a sprinkler is used to frequentlyspray water on the surface of the artificial turf. However, the sprayedwater does not stay on the surface for a time sufficient to cool theartificial turf and rapidly escapes through the holes of the backing 10a. If the size and number of the holes of the backing 10 a are reducedto block the water escaping, rainwater gathers between the infill layer12 and the backing 10 a during a heavy rainfall, causing the infills 13and 14 to float on the water. After the heavy rainfall, the infill layer12 has different densities at different points, losing its function.This may bring about deterioration of playability.

The adjustment of the content of the infills 13 and 14 having a diameterof 1 mm or less to a predetermined level, preferably 10 wt % or more,more preferably 30 wt % or more, with respect to the total weight of theinfills can minimize the spaces between the particles, leading to amarked increase in the retention time of water. As a result, a rise inthe temperature of playground can be prevented. In addition, even duringa heavy rainfall, rainwater is not allowed to stay only between theinfill layer 12 and the backing 10 a and is distributed between theinfills 13 and 14. This prevents the infills 13 and 14 from being sweptaway.

The elastic infill 13 may be present in a larger amount than thehigh-hardness resin infill 14. In this case, as the particle size of theelastic infill 13 increases, the spaces between the particles increase,thus tending to cause excessive elasticity of the artificial turf. Thefine particles fill the spaces to render the infill layer compact. Thiscompactness can moderate the excessive elasticity of the artificial turfas a whole.

The suitable artificial turf infill is not limited to a mixture of theelastic infill 13 and the high-hardness resin infill 14, each of whichis a single kind. Thus, the suitable infill may include a mixture of theelastic infill 13 and the high-hardness resin infill 14, each of whichis at least two kinds having different colors and shapes. A mixing ratioof the elastic infill 13 to the high-hardness resin infill 14 may bevariously selected according to uses. In general, the mixing ratio mayrange from 9:1 to 1:9, preferably from 8:2 to 2:8, more preferably from7:3 to 3:7, and most preferably from 6:4 to 4:6. If the mixing ratioexceeds 9:1, Gmax value may be less than 80, so that the players have ahigh probability of receiving injuries to their ankles, knees, andwaists. In contrast, if the mixing ratio is less than 1:9, Gmax valuemay exceed 200 so that the players can have a g high probability ofreceiving a lethal injury to their heads when falling down while playinga game. Here, Gmax value means a measured value in a shock test and canbe measured on the basis of ASTM F355-A.

FIGS. 3A and 3B are cross-sectional views illustrating other embodimentsof artificial turf having an artificial turf infill. FIG. 3A shows anartificial turf in which a pile fabric 31 having a backing 30 a and pileelements 30 b is filled with an infill layer 32. Here, the infill layer32 is divided into a lower layer having an elastic infill 33 and anupper layer having a high-hardness resin infill 34. Unlike FIG. 3A, FIG.3B shows an artificial turf in which the infill layer 32 is divided intoa lower layer having high-hardness resin infill 34 and an upper layerhaving the elastic infill 33. In consideration of shock absorbency andefficiency of the playing field, the infill layer 32 may be used in sucha manner that the layers having the elastic infill 33 and thehigh-hardness resin infill 34 are respectively stacked as the upper andlower layers thereof, or vice versa. Further, the upper and lower layersmay each have various thicknesses according to the usage.

In detail, the artificial turf infill may be used in a two-layeredstructure in which the upper and lower layers are separated from eachother according to the kind and use of the artificial turf as describedabove, or in a multi-layered structure, instead of being used in aone-layered structure in which the elastic infill and the high-hardnessresin infill are mixed.

According to the foregoing, the artificial turf infill disclosed hereinuses a new infill in place of sands used as a conventional infill, sothat it is possible to overcome the problem of hardening the artificialturf due to sand compaction and the problem of being contaminated byvarious bacteria or germs due to a porous sand structure. The kind andthe mixing ratio of the elastic infill and the high-hardness resininfill are properly selected to reduce a specific gravity difference, sothat a variety of physical properties can be stably maintained incontinuous use. The artificial turf having the abovementioned artificialturf infill has elasticity, hardness, and sliding resistance withoutpartiality, so that it is possible to prevent the players from beinginjured and improve playability.

Hereinafter, the technology disclosed herein will be described in moredetail with reference to some examples.

EXAMPLES

Preparation of samples: As shown in Table 1, infill chips were made invarious mixing ratios and were subjected to measurement of hardness andspecific gravity.

TABLE 1 Hardness and Specific Gravity of Elastic Infill andHigh-hardness Resin Infill Elastic Infill High-hardness Resin InfillTR-1 EP-1 EP-2 EP-3 TP-1 PE-1 PE-2 PE-3 PP-1 Tire 100 EPDM 100 100 100SEBS 100 HDPE 100 100 100 PP 100 Sulfur 2.00 2.00 2.00 M 1.50 1.50 1.50TS 0.50 0.50 0.50 Stearic 1.00 1.00 1.00 Acid Zinc Oxide 5.00 5.00 5.00Calcium 50 250 500 200 50 200 400 300 Carbonate Paraffin Oil 20 20 20 20Chip Pulverization Pulverization Pulverization PulverizationPelletization Pelletization Pelletization Pelletization PelletizationProduction Mode Hardness 65 40 75 90 75 (Shore A) Hardness 65 66 67(Shore D) Hardness 110 (Rockwell R) Specific 1.15 1.13 1.60 1.90 1.551.20 1.65 1.94 1.74 Gravity Content: weight part SEBS: Styrene EthyleneButadiene Styrene Block Copolymer HDPE: High Density Polyethylene PP:Polypropylene Homopolymer M: Mercaptobenzothiazole TS:Tetramethylthiuram Monosulfide

The following tests were performed on mixtures produced by mixing atvarious ratios the infill chips made in the above mixing ratios, and theresults were provided in Table 2.

1. Shock Test: The mixture as an infill was spread on a pile fabric at athickness of 35 mm, thereby making an artificial turf. Then, Gmax valueof the surface of the artificial turf was measured by the shock test,ASTM F3550-A.

2. Distribution Test: A soccerball was bounced 1000 times at a height of50 cm within the artificial turf having an area of 30 cm×30 cm, and thena distribution status of the infill chips was examined at the center ofthe artificial turf.

TABLE 2 Shock and Distribution Test Results According to Mixture ofVarious Elastic Infills and High-hardness Resin Infills Specific GravityDifference Mixing Ratio Gmax (%) Distribution Status TR-1:PE-1 = 10:1 754 Uniform Distribution TR-1:PE-1 = 1:10 220 4 ″ TR-1:PE-1 = 4:6 110 4 ″TR-1:PE-2 = 4:6 120 35 Separation between TR-1 above and PE-2 belowEP-1:PE-2 = 8:2 70 46 Separation between EP-1 above and PE-2 belowEP-2:PE-1 = 6:4 100 33 Separation between EP-2 below PE-1 aboveEP-2:PE-2 = 5:5 110 3 Uniform Distribution EP-3:PE-1 = 9:1 250 58Separation between EP-3 below and PE-1 above EP-3:PE-3 = 6:4 300 2Uniform Distribution EP-2:PP-1 = 8:2 180 9 ″ TP-1:PE-2 = 4:6 120 6 ″TP-1:PP-1 = 1:10 300 12 ″ Accepted Range of Gmax value: 80 through 200

It can be seen from the results of Table 1 that, as the content of theinorganic filler increases,—the hardness and specific gravity of theelastic infill and the high-hardness resin infill are also increased. Itcan be seen from the results of the distribution test of Table 2 that,in the case of the artificial turf infill in which the elastic infill ismixed with the high-hardness resin infill, the distribution status isnot maintained when the specific gravity difference between the elasticinfill and the high-hardness resin infill exceeds about 30% with respectto the smallest specific gravity. When the elastic infill (EP-3) havingan excessive content of filler and the high-hardness resin infills (PE-3and PP-1) are used, the hardness greatly increases—so that the value ofGmax may deviate from the accepted range depending on the mixing ratio,but it can be seen from the results of the shock test that the kind andthe mixing ratio of the elastic infill and the high-hardness resininfill are properly selected so that the desired physical properties canbe adjusted to be suitable for uses.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and various modifications may be made in the scope andspirit of the present disclosure. Accordingly, the various embodimentsdisclosed herein are not intended to limit the true scope and spiritbeing indicated by the following claims.

What is claimed is:
 1. An artificial turf, comprising: a pile fabric having a backing, and pile elements extending upwardly from the backing; and an infill layer filled on the backing such that the pile elements are at least partially embedded in the infill layer, wherein the infill layer includes a high-hardness resin infill substantially substituting for sands used as a conventional infill, and an elastic infill.
 2. The artificial turf according to claim 1, wherein the high-hardness resin infill has a hardness ranging from 50 Shore D to 120 Rockwell R.
 3. The artificial turf according to claim 1, wherein the high-hardness resin infill is made of at least one polymeric material selected from the group consisting of polyethylene, polypropylene, and ethylene copolymer.
 4. The artificial turf according to claim 1, wherein the elastic infill has a hardness ranging from 40 to 90 Shore A.
 5. The artificial turf according to claim 1, wherein the elastic infill includes at least one selected from the group consisting of waste tire recycled chips, thermoplastic elastomer chips, and special rubber chips.
 6. The artificial turf according to claim 1, wherein the content of the infills in the shape of a pellet with a diameter of 1 mm or less in the infill layer is 10 wt % or more with respect to the total weight of the infills. 